If you are backing them blindly the answer is a definite NO.
If you back all odds on horses to win then you have a negative ROI of nearly 4%!!!! Laying is better but still a loss at -1.5% ROI.
So do any angles exist to profit from odds-on horses?
Well laying all odds on Favourites in NHF race over the last 3 years showed a 13pt profit with 3% ROI. This is in fact pretty good.
A Laying SR around 55%
All you need to do is be a little more selective and you can increase those profits.